At the beginning of each player's end step, if no creatures died this turn, Titan Hunter deals 4 damage to that player.
{1}{B}, Sacrifice a creature: You gain 4 life.
If a creature dies while Titan Hunter’s triggered ability is on the stack, Titan Hunter won’t deal damage to that player.
Titan Hunter’s triggered ability triggers at the beginning of each player’s end step, including yours, if no creatures died during that turn.
You can sacrifice Titan Hunter to pay the cost of its activated ability.